The Nant Llech is a minor river in Powys, Wales and which lies wholly within the Brecon Beacons National Park. The name means 'slab stream', presumably in reference to the sandstones across which it runs. Its headwater streams, the Nant Llech Pellaf and the Nant Llech Isaf join forces at Blaen Llech and then continue westwards as the Nant Llech for 3 km / 2 mi to a confluence with the River Tawe just east of the village of Abercraf.[1]